[perl #41827] ICU endian issues causing test failures.

[Joshua Isom]

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I keep getting a test failure on t/op/stringu.t with test 25 on
ppc-darwin(and likely all big endian systems with icu installed).
Parrot outputs "\x00A\x00B" when the test expects "A\x00B\x00" to be
printed. I got a hint to the problem at the icu
faq(http://icu.sourceforge.net/userguide/icufaq.html). "A Unicode
string is currently represented as UTF-16. The endianess of UTF-16 is
platform dependent. You can guarantee the endianess of UTF-16 by using
a converter. UTF-16 strings can be converted to other Unicode forms by
using a converter or with the UTF conversion macros."